An optical storage device is disclosed, and more particularly, a control circuit of an optical storage device and related method thereof is disclosed.
The advancements in computer processing speed and the development of the Internet have resulted in data storage requirements growing tremendously. Many optical discs, for example, digital versatile discs (DVD), are popular due to their characteristics of compact size, large storage capacity, and low price. Therefore, the corresponding optical storage devices, for example, the DVD drives or the DVD burners, are standard devices found in use with typical modern computers.
Please refer to FIG. 1, which is a diagram of a control circuit of a disc tilt control device inside an optical storage device according to US Patent Application Publication No. 2003/0147315. Please note that some devices are not shown in FIG. 1. The tilt control circuit at least comprises: a tracking error signal calculating unit 10, a loop level calculating unit 11, a system control unit 12, a radial tilt control unit 14, and a tracking servo unit 15. The tracking error signal calculating unit 10, the loop level calculating unit 11, and the tracking servo unit 15 can be utilized to form a tilt measuring device of a disc. The system control unit 12 can utilize detected loop level to represent the tilt amount and generate a control parameter according to the detected loop level to control the tilt angle between the disc 1 and the optical pickup head 3.
Please refer to FIG. 2, which is a detailed diagram of a tilt angle measuring device of the optical storage device shown in FIG. 1. As shown in FIG. 2, the portion indicated by a dashed line box is a detailed structure of the loop level calculating unit 11 shown in FIG. 1. The loop level calculating unit 11 comprises: band pass filters 1131 and 1141, full-wave rectifier 1132 and 1142, and low pass filters 1133 and 1143. The signal generator 112 can generate a disturbance signal of a sine wave. The output signal Vt generated by the tracking error signal calculating unit 10 is the conventional tracking error signal (TE signal). The loop level calculating unit 11 processes the TE signal and the signal added by the adder 111 through the band pass filters, the full-wave rectifier s, and the low pass filters to respectively obtain two loop level signals Vin and Vout. The ratio of the loop level signals Vout and Vin is the open loop gain. There is a corresponding relationship between the open loop gain and the tilt amount. Therefore, the system control unit 12 can obtain the corresponding relationship between the open loop gain and the control parameter according to the loop level signals Vin and Vout to control the tilt angle between the disc 1 and the optical pickup head 3.
As mentioned previously, the system control unit 12 can obtain the loop levels corresponding to several control parameters. The system control unit 12 can select an optimized tilt angle control parameter according to these loop levels. However, because the calculation of the loop gain of the optical storage device requires a divider, this is complex to implement.